Last week I found a lump on one of my breast. It is the size of a half dollar. I went to planned parenthood to get check out. Is it hormones?

LARGE Breast mass. A 'breast lump' 2-3cm (>1 in.) in size is signifigant. If you are <30 yo the diagnosis could be a fibroadenoma or a cyst. If >30 yo breast cancer has to be in the differential (possible causes). Either way an ultrasound (&mammogram) and consult with a breast surgeon is recommended. 'hormones' did not cause the lump per se, but may cause it to grow.
Breast lump. This should be immediately evaluated. Your doctor will likely order an ultrasound and/or mammogram. Any breast lump newly noted warrants investigation. There are many benign breast lumps and cysts which may enlarge in response to the hormonal changes of the menstrual cycle, but all should be checked out by a physician to rule out other more worrisome pathology.